Lightweight panel



June 4, 1968 J. l.. GIOVANNUccl 3,386,221

LIGHTWEIGHT PANEL ATTORNEYS United States Patent O 3,386,221 LIGHTWEIGHT PANEL Julius L. Giovannucci, Rome, N. assignor to Revere Copper and Brass Incorporated, Rome, N.Y., a corporation of Maryland Continuation-impart of application Ser. No. 425,225,

Jan. 13, 1965. This application Sept. 8, 1967, Ser.

1 Claim. (Cl. 52-S86) ABSTRACT F THE DISCLOSURE An extensible structural panel system in which websupported thin skin members of interconnected .panels are provided with thickened port-ions extending beyond the end-most we'bs to form rigid channels which are joined by a snugly-fitting rectilinear coupling member the end portions of which are spaced apart by a lesser distance th-an that between the webs forming the b-ases of -opposing channels when the edges of the thus-connected panels are in abutment.

This application is a continuationdn-part of my c0- pending application Ser. No. 425,225, led Jan. 13, 1965 and now abandoned.

The present invention relates to lightweight high strength structural panel-ing, and in particular it relates to a system of interconnected extruded aluminum panels of the so-called honeycomb panel type capable of forming large rigid planar structures.

A well-known ty-pe of composite structural panel that combines high strength with low weight comprises two substantially parallel outer sheets or skin members separated from `each other by a lightweight center core that is secured to the inner surfaces of the outer skins. This type of panel is frequently employed as a structural element in aircraft, ships and the like where its inherent properties of high strength and low weight are highly desirable. Such lightweight panels are customarily fabricated from sheets of relatively thin gauge metal, the two outer metal sheets or skins generally being connected by an inner honeycomb core structure formed from the same material that is brazed or otherwise secured to the inner sur-faces of the two skins or is formed from a dissimilar material to which the skins are secure-d by .an adhesive or the like.

The fabrication of a conventional honeycomb panel can be both diicult and expensive. For example, the inner core must first be fabricated and then assembled with the two outer skins to form the composite honeycomb structure, .and then the three parts of the composite must be firmly secured or bonded together by a brazing or welding operation or the like. Problems inherent in the complicated fabricating, assembly and bonding operations make it diicult to eliminate minor imperfections in the final product. Moreover, when a number of conventional honeycomb panels are being assembled edge-to-edge to form a larger structure (such as a wall or a floor), the smooth and eicient joining of abutting edges of the panels presents many problems difficult to solve.

I -have now developed a new lightweight panel of the so-called honey-comb type that overcomes or eliminates 3,386,221 Patented June 4, 1968 substantially lattice-like configuration. The skin members s are of sufficient thickness that they cooperate with the Webs to impart the required structural rigidity to the panel. At least one edge of the panel is formed with a longitudinal channel defined by opposing edge portions of the skin members and the longitudinal web member adjacent said edge portions, these edge portions of the skin members having a thickness at least 25% g-reater than the remaining portions thereof and being provided with a beveled lead-in at their proximal outboard edges. The tubular .aluminum coupling member has a closed rectilinear shape with two of its opposite planar surfaces spaced apart a distance such that they are adapted to be inserted closely between the inner surfaces of said edge portions of the panel skin members and with its other two opposite planar surfaces spaced apart a distance less than that between the channel-forming web members of the connected panels when the outboard edges of the connected panels are in abutment.

My new panel construction will be better understood from the following description thereof taken in connection with the accompanying `drawing of which FIG. 1 is a perspective view of two of my new panels disposed edge to edge to form a larger structural unit,

FIG. 2 is an end elevation yof my new extruded panel showing the ladder-like configuration thereof, and

FIG. 3 is a fragmentary sectional view showing the joining of abutting longitudinal edges of two panels t0- gether pursuant to the invent-ion.

My new honeycomb panel is integrally extruded in one piece by conventional aluminum extrusion techniques, :a typical panel being in the order of 7 feet in length, 1 foot in width and 1 inch in over-all thickness. two such panels 10 are shown joined edge to edge in PIG. l of the drawing.

As shown best in FIG. 2, my lightweight extruded aluminum panel 10 comprises a first outer skin member 11, a second outer skin member 12 substantially parallel to and spaced apart from the first outer skin member 11 by a plurality of longitudinally extending web members 13 integrally formed with the two outer skin members in the course of the extrusion of the panel. The longitudinal web members 13 are spaced substantially eq-uidistant from each other. The two substantially parallel outer skin members 11 and 1-2 and the plurality of equi-spaced longitudinal web members 13 disposed tl1erebetween together present a unique ladder-like 'honeycomb configuration when viewed from one end as clearly shown in FIG. 2. The integrally formed panel of my Iinvention possesses an unusually high strength-to-weight ratio. The outer skin members 11 and 12 are of sufiicient thickness that they cooperate with the web mem-bers 13 and impart the required structural rigidity to the panels so that they resist bending forces.

At .least one longitudinal edge of the panel is formed with a longitudinal ch-annel dened by the adjacent edge portions of the two outer skin members 11 and 12 and the web member 13 adjacent the longitudinal edge. The longitudinal channels 15 formed along the longitudinal edges of the panels of my invention f-acilit-ate rigid and smooth edge to edge joining of two adjoining panels. For this purpose, the projecting edge portions of the skin members are provided with a thickness at least greater than that of the remainder thereof rand are further provided with a beveled lead-in 15a at their proximate outboard edges. To effect the edge-toedge juncture of two ladjoining panels, a tubular coupling member 16 is advantageously formed of extruded aluminum or is formed from sheet metal having a locked, crimped or brazed joint so as to form a closed rectilinear shape having the rigid-ity of a simple tubular shape. The coupling member is inserted into the longitudinal channels 15 of the adjoining panels as shown in FIG. 3. The opposite planar surfaces 16a and 1611 engaging the projecting edges of the skin members 11 'and 12 are so spaced that they lit snugly, but not necessarily tightly, therebetween -and the other two opposite planar surfaces 16e and 16d are spaced apart a distance less than that between tbe channel-forming web members of the connected panels when the outboard edges of the connected panels are in abutment. The resulting juncture effected between adjoining edges of the two panels may be of a temporary nature in which case the tubular coupling member 16 is he-ld in the longitudinal channels 15 mainly by frictional forces, or the juncture can be made permanent by welding or otherwise permanently securing the tubular coupling member 16 in place in the longitudinal channels 15 of the two adjoining panels. In either event, the lconnected panels oder suicient rigidity to permit the yformation of large planar structures requiring no eX- traneous lateral support.

It will be appreciated, accordingly, that the panel system of the invention offers structural rigidity with light weight. The honeycomb structure of the panels permits their extrusion from aluminum, and the web members being integrally formed with the skin members permit the use of thin skin members without sacrificing rigidity. The extra thickness of the channel-forming portions of the skin members insures rigidity along the interconnection of the panels, and the lead-in at the edges of these portions permits insertion of the connectors to form a snug tit. The fact that the connector is of closed rectilinear shape impa-rts rigidity to the connector by preventing the give which is characterized by open connector structures having a channel shape. The size of the con- 4 nector is further such that, when it is inserted between adjoining panels, and the panel edge portions are in abutment, the surfaces of the connector facing the channelbase webs 13 are spaced from the webs so as not to interfere with alignment of the panels or with their abutment.

I claim:

1. An extendible panel system of extruded aluminum parts assembled with other components to form large rigid planar structures, said system comprising a plurality `of light weight extruded aluminum panels and at least one rigid tu-bular aluminum coupling member connected to said panels along at least one longitudinal edge of each of said panels and substantially coextensive therewith,

each of said extruded aluminum panels comprising parallel spaced skin members and a plurality of longitudinally extending spaced web members integrally formed with and connecting the two skin members in a substantially lattice-like configuration, the skin members being of suicient thickness that they cooperate with the webs to impart the required structural rigidity to the panel, at least one edge of the `panel being formed with a longitudinal channel deiined by opposing edge portions of the skin members and the longitudinal web member adjacent said edge portions, said edge portions of the skin members having a thickness at least 25% greater than the remaining portions thereof, and being provided with a beveled lead-in at their proximal outboard edges, and said tubular aluminum coupling member having a closed rectilinear shape with two of its opposite planar surfaces spaced apart a distance which substantially corresponds to the distance between the inner surfaces of the thickened edge portions such that they are frictional-ly gripped between the inner surfaces of said edge portions of the panel skin members, the other two opposite planar surfaces of the tubular coupling member being spaced lapart a distance substantially less than that between the channel-forming web members of the connected lpanels whereby a space exists lbetween at least one of said other planar surfaces and said web members.

References Cited UNITED STATES PATENTS 1,841,233 1/'1932 Whiting 52-595 2,457,129 12/ 1948 Collings 52-1627 2,680,604 3/1953 Marsh 52-573 V3,192,671 7/1965 Smith 52-586 3,301,147 1/1967 Clayton et al. 52--588 HENRY C. SUTHERLAND, Primm-y Examiner. 

